Conventionally, examples of a scheme for sharing data between multiple terminals include a server-client scheme and a peer-to-peer (Peer to Peer) scheme. In a server-client scheme, a server terminal collects all data from client terminals and performs arithmetic processing. The server terminal transfers arithmetic processing results to the client terminals. In a peer-to-peer scheme, terminals on a network exchange data, and each terminal performs arithmetic processing. “Peer to Peer” may be abbreviated as “P2P”. In the description herein, the server client is abbreviated as “CS”, and “Peer to Peer” is abbreviated as “P2P”.
Under both the P2P scheme and the CS scheme is a system having advantages of both schemes and in which a management server receives a registration request and an access request for data shared between client devices, and each client device stores therein data and accesses the data upon receiving an approval response from the management server. For an example, refer to Japanese Laid-Open Patent Publication No. 2006-11693
Nonetheless, in a conventional CS system, although power consumption of the entire system can be reduced since one terminal performs arithmetic processing, from the collection of data until the completion of transfer of the arithmetic processing result takes time because data communication is performed between the server terminal and the respective client terminals at the time of data collection and transfer of the arithmetic processing result. On the other hand, in a conventional P2P system, data communication is only performed at the time of inputting data to a terminal from another terminal. Therefore, only a short period of time is consumed from the input of data until the completion of the arithmetic processing. However, because each terminal performs arithmetic processing, power consumption of the entire system increases. It is therefore desirable to share the data in a CS system when power consumption of the entire system including the arithmetic processing by each terminal is desired to be reduced, and to share the data in a P2P system when high-speed processing is desired.